Asymptomatic children might transmit human parechovirus type 3 to neonates and young infants

Background: Human parechovirus type 3 (HPeV3) epidemics occur worldwide and can lead to severe disease in neonates and young infants. Little is known about the source of HPeV3 infection. Objectives: To investigate the source of HPeV3 infection and the role of asymptomatic children in the families of infected children. Study design: During a 2014 HPeV3 epidemic in Niigata, Japan, we analyzed (1) clinical information on sick contacts for 43 neonates and young infants with HPeV3-related disease diagnosed by PCR analysis of serum and/or cerebrospinal fluid and (2) stool samples from symptomatic and asymptomatic siblings/cousins of index patients. To confirm transmission, the P1 (VP0, VP3, and VP1) and 3D(pol) regions of HPeVs were sequenced and analyzed. Results: Sick contact with family members was confirmed for 51% (n = 22) of patients. Among the 30 symptomatic family members, 67% (n = 20) were siblings, 20% (n = 6) were mothers, and 13% (n = 4) were other relatives. Stool samples from symptomatic and asymptomatic siblings/cousins of 4 HPeV3-infected patients yielded positive results for HPeVs on PCR analysis. Furthermore, the P1 and 3Dpol nucleotide sequences of family members were 100% identical to those of the respective index cases. Conclusions: Identification of genetically identical virus from HPeV3-infected patients and asymptomatic children in their families suggests that the latter are a source of infection in neonates and young infants with HPeV3-related diseases. (C) 2015 Elsevier B.V. All rights reserved.